Obiwan's old appearance!
I began to realize that people at age 50 doesn't look old at all, they do keep some of their youth. Now Obi wan in episode 4 was in his mid 50s yet he looked as if he was in his 70s or 80s. With clone wars, We learned that Obiwan is known for taking in disguises. Is his aging meant to be a disguise or does something happen to him that causes him to age faster. Is Obiwan a clone of someone and never knew it? Clones have been known to age fast.